Rotary cutter



A. M. SIMPSON.

ROTARY CUTTER. APPLICATION FILED auuz21. 1921.

1,396,600. WMNOV. 8,1921.

,Fgz. 2:1 2.

UNITED STATES PATENT OFFICE.

ROTARY CUTTER.

Application filed June 27, 1921.

To all whom it may concern:

Be it known that I, ALFRED M. SIMPSON, a citizen of the United States,residing in the city of Honolulu, Territory of Hawaii, have inventedcertain new and useful I'mprovements in Rotary Cutters; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains, to make and use the same.

The invention relates to rotary cutters for sugar cane and the like, andhas for its object to provide a simple, strong, durable and efficientdevice of the character indicated, comprising a shaft and a plurality ofknives having radial blades spaced along said shaft and rigidly securedthereto by suitable means, which admit of individual knives beingreadily removed and replaced, and which also prevent the distortion ofthe knives under heavy stresses imposed thereon in the cuttingoperation.

The invention is illustrated in the accompanying drawings, in whichFigure 1 is a vertical side elevation of a single knife and theassociated shaft, the latter being shown in section;

Fig. 2 is a front elevation of a section of the shaft having a number ofknives secured thereto; and

Fig. 3 is a horizontal section on line 33 of Fig. 1, with the shaftomitted.

Referring to the drawings, 1 indicates a shaft, which is preferablycylindrical in form and is provided with a series of longitudinalkeyways 2, spaced at regular intervals about the periphery thereof andserving as part of the primary means for locking the individual knivesto the shaft. In the particular embodiment of the invention illustrated,four of said keyways are shown spaced 90 apart.

Each of the knives comprises a hub section 3, which is relatively thick,terminating body portion of each cutter being formed as an integralcasting, which, because of the Specification of Letters Patent.

Patented Nov. 8, 1921.

Serial No. 480,811.

is exceptionally strong and is effective in resisting the tendency ofcutters of this character to rupture at the points of juncture betweenthe blades and the hub. The hub 3 is provided with a centralshaft-engaging opening 4, the major portion of which hugs the shaft,said opening 4 being extended laterally of one side of the hub, as anopen throat to permit the cutter to be passed over the shaft. Formed inthe body of the hub at each side of the open throat is a shoulder 7,provided with a generally rectangular recess 8 in the bottom thereof.Each of the shoulders 7 is also provided with a tapped bolt hole 9,which preferably registers centrally with the corresponding recess 8.

The throat or lateral opening in the hub 3 is closed by a cap 10, theinner surface of which conforms with that of the shaft 1, which itclosely engages when in position, and is provided with lateral wings 11,which engage the shoulders 7 in the hub, each of said wings beingprovided with a rib or boss 12, which fits in the recess 8 in thecorresponding shoulder 7. The arcuate shaftengaging surface of the capis provided with a keyway 17, adapted to receive a key 15, which issubstantially rectangular in cross section and extends beyond the faceof the cap to engage one of the keyways 2 in the shaft 1. The key 15 isprovided with a central transverse openin to receive a bolt 16, by meansof which the key is securely locked to the cap. It will be particularlynoted that the key 15 is of a length slightly greater than the thicknessof the hub 3, so that the ends of the key project slightly beyond thelateral faces of the hub. The cap is secured to the hub by any suitablemeans, but preferably by threaded bolts which are passed through boltopenings in the wings 11 and screwed into the bolt openings 9 in thebody of the hub. The outer end of each of the bolts 18 is provided witha double lock nut 1%, by means of which the caps are drawn into closeinterlocking engagement with the huh, as shown.

In assembling the rotary cutter, the sevcral knives are mounted on theshaft with the radial blades of alternate knives at right angles to eachother, which is effected by sliding the knives laterally over the shaftand then applying each cap 10 to its hub, so that the key 15 carried byeach cap will engage the appropriate keyway 2 in the shaf The provisionof four keyways 2 in the shaft enables the knives tobe so disposed thatthe key connections between the successive knives of the series will bespaced 90 apart around the shaft, thereby distributing the torsionalstressesevenly about the shaft and reducing the tendency of the knivesto rupture or twist off, which is a common faultin devices of thischaracter when a single keyway in'the shaft is provided for connectingall the knives thereto. It will alsobe noted that the interlock betweenthe wings 11 of the cap and the shouldered recesses 7 in-the hub, andalso between the ribs 12 on the wings 11 and the recesses 8 in theshoulders 7 of the hub, materially strengthens the structure andprevents any opening or distortion of thethroat of the hub due to theheavy" stresses imposed upon the cutters when in operation. Then thecaps 10 have beenset firmly inposition by means of the locknutslelengaging the threaded bolts 13, the concave faces of the capsafford an additional clamping means for securing the cutter'to the shaftand materially lessening the shearing stresses on the keys 15.

"From the foregoing descriptionit will be apparent that the deviceinvolves material improvementsancl advantages over former types ofrotary cutters,and among the points ofsuperiority in this particularconstruction maybe mentioned the following :The'hub andthe blades arecast integral, which admits of a relatively wide filleted shoulder,suchas5, being formed between the hub and the knives, which greatlystrengthens the individual cuttersandeliminates the tendenc'y torupture, which is common in the older types of cutters, wherein theknives are either bolted to ahub 'or' clamped between adjacent hubs.Each hub being held in'its position independently of all other hubs, andthere being no side strain between adjacent hubs, thetendency of theshaft to twist or distort under the heavy torsional strain ispractically eliminated. This matter of distortion of'the shaft'hasproven a serious difficulty. in all former types of cutters of thisgeneral character, in which the hubs of'the several knives are clampedtogether by longitudinal bolts or by heavy nuts on the ends of theshaft. The provision of the keys 15 of slightly greater length than thethickness of the hubs, so that the ends of the keys project beyond thelateral faces of the hubs, affords an effective spacing means to holdthe knives in proper spaced relation, so that adjacent hubs do notcontact and, therefore, do not tra nsinit the strains imposed thereon toadjacent hubs or cutters. Any one of the cuttersmay be readily replacedwithout moving or in any way interferlng with the adjacent cutters. Theperfect balance of the apparatus will-not be disturbed even if one ormore of the cutters is removed entirely.

' What I claim is:

1. A rotary cutter comprising a shaft having a series of peripherallyspaced longitudinal keyways therein, a series of separate knives mountedon said shaft, each knife including a thick hub section and thinnerintegral radial blades, and separate keys connecting the knife hubs tothe shaft, each key having a length greater than the thickness of thehub and serving to engage and space adjacent knives.

2. A rotary cutter comprising a shaft having a-series of peripherallyspaced longitudinal keyways therein, a series of separate knives-mounted on said shaft, each knife including a thick'hub section andintegral radial blades having filleted shoulders at their junctions withthe hub sections, and separate keys connecting the knife hubs to theshaft, eachkeyhaving a length greater than the thickness of the hub andserving ooenin' a ca closin said 0 enin and radial blades, and keysengaging keyways in the shaft and knivesto lockthe latter to the shaft.

5. A knife forrotary cutters comprising a central hub, integral radialblades of less thicknesshaving filleted shoulders at their junctionswiththe hub sections, said hub having a shaft-engaging opening and alateral opening communicating therewith, shoulders formed adj acent saidlateral opening, a cap fitting said lateral opening and engaging saidshaft, means for securing the cap to the hub, and a key carried by thehub for locking the knife to a shaft.

6. A knife for rotary cutters comprising a central hub, integral radialblades of less thickness thanthe hub, said hub having ashaft-engagingGopening, a lateral opening communicating therewith andhaving shoulders formed thereon at the sides of said lateral openingandha'vin'g recesses therein, a cap fitting said 'lateral opening havinga shaft-engaging portion andwings engaging said shoulders, lugs on saidwings engagin said recesses, and means for locking sai cap to the hub.

7. A knife for rotary cutters comprising a central hub, integral radialblades of less thickness having filleted shoulders at their junctionswith the hub section, said hub having a shaft-engaging opening and alateral opening communicating therewith and shoulders formed thereonadjacent said lateral opening, a cap fitting said lateral opening andengaging said shaft, means for securing the cap to the hub, said caphaving a keyway in its inner face, and a key in said keyway to engagethe keyway in a supporting shaft.

8. A knife for rotary cutters comprising a central hub, integral radialblades of less thickness than the hub, said hub having a shaft-engagingopening, a lateral opening communicating therewith and having shouldersformed thereon at the sides of said lateral opening and having recessestherein. a cap fitting said lateral opening having a shaft-engag1ngportion and wings engaging said shoulders, lugs on said Wings engagingsaid recesses, said cap having a keyway on its inner face, and a key insaid keyway to engage the keyway in a supporting shaft.

9. A knife for rotary cutters comprising a central hub having ashaft-engaging opening with an open lateral throat, a cap closing saidthroat and having a keyway in its inner face, a key secured in saidkeyway means to secure the cap to the hub, and radial blades formedintegrally with said hub.

In testimony whereof I aflix my signature.

ALFRED MERVYN SIMPSON.

